1. Field of the Invention
The present invention relates to controlling a supply of a developer. More particularly, the present invention relates to a method and a device for controlling a supply of a developer to a developing device to maintain an amount of the developer contained in the developing device equal to or greater than a predetermined amount.
2. Description of the Related Art
An image forming apparatus such as a laser printer includes an exposing unit and a developing unit. The exposing unit forms an electrostatic latent image by exposing a photosensitive drum to light in accordance with given print data. Also, the developing unit develops the electrostatic latent image by using a developer. The development result is transferred on a print medium and output as a printed image.
The developing unit includes one or more developing devices. Specifically, a developing unit of a mono laser printer that performs black-and-white printing includes one developing device, and a developing unit of a color laser printer that performs color printing includes a plurality of developing devices.
An amount of the developer equal to or greater than a predetermined amount has to be contained in the developing device to prevent a poor quality image with low printing concentration, which is visible to the naked eye from being output.
Although the amount of the developer may always remain equal to or greater than the predetermined amount in a conventional image forming apparatus, printing is performed even when the amount of the developer is very low. Therefore, a low quality image is occasionally printed. Accordingly, techniques for controlling the developer supply to the developing device are required to maintain the amount of the developer contained in the developing device equal to or greater than the predetermined amount.